Toolholder



Feb. 2, 1954 F. H. CLARKSON 2,667,687

Filed Nov. 19, 1951 Inventor Frank Henry Clarkson.

E/ MQ W Attorneys.

Patented Feb. 2, 1954 UNITED STATES PATENT;oFrlce-if1 Frank Henry Clarkson, Coventry,England Application November 19, 1951, Serial No. 257,140 3 Claims. 29103) This invention relates to milling cutters and like rotary machining tools and shanks or the like therefor and has for its object to provide means on a shank whereby a cutter or like tool may be detachably mounted by screwing the tool thereon, said means in accordance with this invention incorporating release mechanism whereby a cutter or the like that has become tightly screwed onto its shank after a machining operation can be freed so that it may be readily detached by unscrewing.

The present invention is particularly applicable to the mounting of larger sized milling cutters especially end mills e. g. those over 1 /2" in diameter.

In order that the invention may be readily understood and carried into practical effect reference is made to the accompanying drawing which is an elevation of a shank according to this invention mainly in axial plane section to reveal the construction of same.

In carrying the present invention into practice a preferred form is shown and hereinafter described as applied to the mounting of a milling cutter I on a shank 2 therefor.

The milling cutter I is provided with a coaxial threaded bore 3 which may be blind, whilst the shank 2 therefor is also provided with a coaxial bore 4 to receive a co-axial member in the form of a plug 5 which plug extends from the end of the shank 2 and is screw threaded at B to receive the milling cutter I screwed thereon.

The arrangement is such that the end face I of the milling cutter I may be screwed up to firm abutment against a similar surface 8 at the end of the shank 2.

As shown the milling cutter I has a spigotted engagement about a reduced portion 9 of the shank 2, the plug 5 having a flange I0 engaging a transverse groove II across the end of the reduced portion 9 to positively prevent rotation of the plug 5 relative to the shank 2.

In order to normally restrain the plug 5 against axial movement in the shank and also provide release means to enable the milling cutter I to be freed for unscrewing, a transverse pin or the like release member I2 is provided which is arranged to pass through transverse bores I3, I4 in the shank 2 and plug 5 respectively.

In the preferred form of this invention shown the pin I2 is provided with an inclined surface I 5 after the manner of a cotter pin and co-operates in a wedge-like manner with a complementary surface I6 formed by inclination of the transverse bore I4 in the plug 5.

When the milling cutter I is screwed onto the threaded portion 6 of the plug and into abutment with the end face 8 of the shank 2, the said pin I2 restrains the plug 5 against axial movement in the shank 2 so that the milling cutter I is firmly mounted in position. When it is desired to free the milling cutter I for unscrewing after a series of milling operations when the cutter has become extremely tightly screwed against the shank 2, means in the form of the screw I1 is provided for imparting axial movement to. the pin I2 against the frictional load on the latter so that the co-action of the inclined surface I5 of the pin I2 with that of the plug 5 permits a limited degree of axial movement of the latter in an outward direction from the shank 2 sufiicientto enable the milling cutter I to be freed so that it may be readily unscrewed by hand. For this purpose the inclined surface I5 of the pin I2 is on that side of same remote from the milling cutter I, and the angle of inclination is of the order of 15 to provide a non-locking angle.

In order to urge the pin I2 to abutment with the screw I! for the purposes of resetting the pin, the recessed end of said pin I2 remote from the screw II has bearing against same a compression spring [8 which takes abutment in a recessed screw I9 plugging the end of the transverse bore I3 in the shank 2. The screw I1 is preferably provided with a hexagonal recess 20 to receive an Allen key so that the screw may be turned to impart axial movement to the pin.

Thus with milling cutters and shanks therefor it accordance within this invention milling operations are expedited in that the milling cutters can be readily removed from the shank after use. Furthermore, the provision of a blind threaded hole in the milling cutter leaves the other end thereof unobstructed for the formation of end milling cutting edges, whilst the fact that the cutter does not require an integral shank enables an economy to be effected in high speed steel or the like metal from which milling cutters and the like tools are usually manufactured.

I claim:

1. A rotary tool and shank therefor comprising in combination a rotary tool having a co-axial threaded bore therein and a shank comprising a shank body part having a co-axial bore in an end face thereof and also a transverse bore closed at one end and communicating with said co-axial bore; a co-axial member no -rotatably located for axial movement in the co-axial bore of said shank body part and having a transverse bore formed with an inclined surface which bore registers with the transverse bore in the shank body part, whilst said co-axial member also has a threaded portion extending from the end face of the shank body part for receiving the rotary tool screwed thereon against said end face; a transverse member located in the transverse bores in said shank body part and oo-axial member and having a complementary inclined surface co-acting with the inclined surface of the transverse bore in the co-axial member,;so-;=that outward movement of the latterrelative-tothe shank body part is prevented except on axial movement of the transverse member; a screw in the transverse bore of the shank body part for abutment with one end of said transverse member in order to impart axial movement thereto for -permitting-limited outward axial member to free the rotary tool for unscrewing from the shank; and a spring between the-closed havingattransverses.bore therethrough substane tiallyuin registerwithttheatransverse; bore of the: shank body-:- part; a} transversel release member: extendingthrouglr said transverse horesfor-endwisetmovementv thereinuand having an inclined; surface: for: wedge-like co-action between the shank:body partand thaco-axial memberto prevent outward axial- -movementof the-latter --re1a-- tiveto said shank bodyepart except-:onmndwise movement: of said: release member; and screw means engaging the shank bod'y part for impartingaendwisemovement to the-release member in order to-permit limited outward axial 'movem'ent; of the oo-axial member to free the v rotary tool-for unscrew-ingfrom the shank? movement of the I co axial;

3. A shank for receiving a rotary tool screwed thereon, comprising a shank body part having a co-axial bore therein open at the forward end and also a transverse bore closed at one end and communicating therewith, said forward end being grooved; a co-axial member located for axial movement in the co-axial bore of said shank body part and having a threaded portion at the forward end of the latter for screw threaded engagement witrra rotary tool'iso that the: latter abuts againstthesaid forward'end of the shank body part, said co-axial member having projections engaging the grooved forward end of the shank bodypart for driving engagement therewith and also having a transverse bore therethrough sub- 7 stan-tially in register with the transverse bore of the shank body part; a transverse release member extending through said transverse bores for endw-ise: movement therein and having an inclined surface for wedge-like co-action between the shanki ;b0dy;:part and the lco-vaxialmemberrto prevent outward axial; movement of the latter; exceptron endwisemovement of said release. r-iem1e ber; a- -screw in ;the transverse :bore of c the shank bedyhpart for; abutment with one end; 0f'5said;-r elease member in-torderto impart:endwisevmovee ment thereto, for permitting"; limited; outward axial movementzof theecmaxialgmembergto free the rotary-tool fOIE I SOLGWiHgL1 150111113116 shank; and aspring betweemtheclosedfend of. thetranse verse bor in the shank bodyipa/rtgand theeother: end of the ;release:;member:for;urgingithe latter o-abutment withsaid'screwz FRANK CLARK SONL' References-Cited in -the file of this'-- patent" UNITED STATES PATENTS Number Name Date-i:

,1 37 My rsi. ,l..tMar:167,.19153- 1,354,097 Fitzsimmonsr. Sept .':28;\l920 1,fi07,7.-32=; Fletcher, Nova; 23,: 1926 3 1,26 1;, Pechacekz .L,Mar. "29;: 1932:: 2,040,263 Iia'yneget. alri kMay -12,;1'936@ 2,400,856 Thompsom; Mayr21;.1'946z 

